1. Field of the Invention
This invention relates to hand tools and, more particularly, to tools for removing bicycle crank arms from the ends of axles.
2. Description of the Prior Art
Bicycle crank arms are typically provided with a compound bore through one end thereof, the inner portion of the bore being substantially square in transverse cross section and the outer portion of the bore being internally threaded, the two portions being separated by a radially extending shoulder. The square portion of the bore is press-fitted over the square end of the axle. One type of axle has an internally threaded female end and another type has a male end with an externally threaded stud projecting therefrom. In the former type the crank arm is locked in place on the axle end by a retaining screw having a flange which bears against the shoulder in the crank arm bore. In the latter type a flanged retaining nut engages the axle end stud.
The crank arm is often difficult to remove from the axle end. Accordingly, puller tools have been provided to assist in removal of the crank arm from the axle end. Such tools typically include an externally threaded tubular insert which threadedly engages in the threaded portion of the crank arm bore after the retaining nut or screw has been removed. The puller also includes a pressure screw which is threadedly engaged through the tubular insert and has a bearing end which bears against the axle end so that, as the pressure screw is rotated, it cooperates with the insert to separate the crank arm from the axle end.
The insert is typically provided with a hex portion which is engageable with an associated hex wrench or the like to facilitate engagement thereof in the crank arm bore. Similarly, the pressure screw may be provided with a polygonal end for engagement by another wrench. This commonly requires the use of two different wrenches.
One type of prior tool, disclosed in U.S. Pat. No. 5,099,726, provides a hex surface on one end of the insert and another hex surface intermediate the ends of the pressure screw and a handle member with a box-type hex wrench opening which can be used on the hex drive surfaces of either the insert or the drive screw. But this requires the use of a separate specialized wrench tool. That device also provides a hex socket on the outer end of the pressure screw which can be engaged with a standard hex drive tool for rotating the screw. Again, the device either requires a specialized wrench tool or two separate wrench-like tools.
Another type of tool manufactured by Park Tools under part no. CCP-1 has an integral handle permanently attached to the outer end of the drive screw and a hex surface on the insert for engagement by a standard hex wrench. However, this still requires a separate wrench to drive the insert and, furthermore, the drive screw handle is only about 61/2 inches long and affords limited leverage. This may be insufficient, because often the torque required to remove the crank arm can approach 100 lb.-feet. Furthermore, the Park Tools device has a conical tip on the bearing end of the pressure screw which can damage the threads of a female axle end.